* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    /* 弹性布局 水平、垂直居中 */
    display: flex;
    justify-content: center;
    align-items: center;
    /* 100%窗口高度 */
    height: 100vh;
    /* 相对定位 */
    position: relative;
    /* 渐变背景 */
    background: linear-gradient(200deg, #2b5876, #033557);
}

.container {
    display: flex;
    /* 允许换行 */
    flex-wrap: wrap;
    /* 将元素靠边对齐 */
    justify-content: space-around;
    .btn {
        position: relative;
        width: 200px;
        height: 60px;
        margin: 30px;

        &:hover a {
            letter-spacing: 5px;
            &::before {
                transform: skewX(45deg) translateX(200%);
            }
        }
        a {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            display: flex;
            justify-content: center;
            align-items: center;
            /* 透明度为0.05的白色背景 */
            background: rgba(255, 255, 255, 0.05);
            /* 阴影 */
            box-shadow: 0 15px 35px rgba(0, 0, 0, 0.2);
            /* 上下边框 */
            border-top: 1px solid rgba(255, 255, 255, 0.1);
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
            /* 圆角 */
            border-radius: 30px;
            color: #fff;
            z-index: 1;
            font-weight: 400;
            /* 字间距 */
            letter-spacing: 1px;
            /* 去下划线 */
            text-decoration: none;
            /* 动画过渡 */
            transition: 0.5s;
            /* 溢出隐藏 */
            overflow: hidden;
            /* 背景模糊 */
            backdrop-filter: blur(15px);
            overflow: hidden;

            &::before {
                content: '';
                position: absolute;
                top: 0;
                left: 0;
                width: 50%;
                height: 100%;
                background: linear-gradient(to right, transparent, rgba(255, 255, 255, 0.15));
                transform: skewX(45deg) translateX(0);
                transition: 0.5s;
            }
        }
        
        &::before,
        &::after {
            content: '';
            position: absolute;
            left: 50%;
            transform: translateX(-50%);
            width: 40px;
            height: 10px;
            background: red;
            border-radius: 5px;
            box-shadow: 0 0 5px red, 0 0 15px red, 0 0 30px red, 0 0 60px red;
            transition: 0.5s;
            transition-delay: 0.3s;
        }
        &::before {
            bottom: -5px;
        }
        &::after {
            top: -5px;
        }
        &:hover {
            &::before,
            &::after {
                height: 50%;
                width: 80%;
                border-radius: 15px;
            }
            &::before {
                bottom: 0;
            }
            &::after {
                top: 0;
            }
        }
    }
}
